Large-area graphene quantized Hall resistance arrays using superconducting interconnections

Next generation quantum resistance standards based on multiple quantized Hall resistance (QHR) elements will allow tailoring the fundamental value to the needs of a given application. However, scalable resistance networks often suffer from accumulated resistances at metallic interconnections that lead to a deviation from the theoretical value.

This work shows the first results of epitaxial graphene-based, QHR array devices using superconducting contacts and interconnections to minimize parasitic resistances. The applied contact design is optimized for reduced contact resistances and circumvents any possible alteration of the QHR caused by Andreev reflections. For homogenous charge carrier concentrations and high monolayer quality, optimized growth and doping techniques were developed to allow for the realization of complex chip designs on the centimeter scale.

The results show different QHR array devices at exceptionally high currents in the mA range that are utilized to improve the measurement uncertainty of relatively simple, room temperature resistance bridges. To ensure the applicability in quantum resistance metrology, we apply and test new global criteria of quantization and verify the precision using direct current comparators and cryogenic current comparator bridges.